Phenotype of lymphocytes associated with the inflammatory reaction to silicone gel breast implants

The tissue response to silicone gel breast implants typically includes an inflammatory infiltrate that consists of macrophages, foreign body-type giant cells, and a variable number of lymphocytes and plasma cells. The phenotype of the lymphocytic component was investigated with three-color flow cytometry. Lymphocytes were obtained by collecting fluid from the space between the implant and the fibrous capsule or by washing cells from the fibrous capsule at the time of implant removal with total capsulectomy. Eighty-nine percent of the implant-associated lymphocytes were T cells. Twenty-five percent of the CD3+ T cells coexpressed HLA-DR compared with only 7.9% of matched peripheral blood lymphocytes. Sixty-eight percent of the implant-associated T cells coexpressed CD4 and CD29, while only 3% of the T cells coexpressed CD4 and CD45RO. The expression of HLA-DR and the predominance of CD29+ CD4+ T cells indicate that there is immune activation with the potential for stimulating antigen-specific antibody production. The role of silicone gel breast implants in immune activation and its clinical significance require further investigation.